Airbag projectile for impeding surface vessel

ABSTRACT

A projectile can be fired at a surface vessel and, upon impact, an air bag may be deployed almost instantaneously from underneath the vessel. Through the rapid inflation of the air bag, the stability and orientation of the target surface vessel may be disturbed. Disturbance, at a minimum, may reduce and change the trajectory of the surface vessel, but, in some circumstances, the surface vessel may be overturned. The air bag may be designed with an anti-slip coating to directly couple to the wet hull of the surface vessel. In some embodiments, the projectile may include a delay to enable the air bag to be positioned under the vessel before inflation thereof.

STATEMENT OF GOVERNMENT INTEREST

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The invention relates to apparatus and methods for impeding motion of awater surface vessel and, more particularly, apparatus and methods forimpeding the motion of a water surface vessel by inflating an air bagunder the surface vessel.

(2) Description of the Prior Art

Conventional methods and devices for arresting small surface vesselsinclude deployable nets designed to foul the propeller mechanism of avessel, fences, inflatable bladders and fixed barriers. While generallyeffective at stopping small surface craft, all are limited in terms offlexibility due to their small area of effect. Stationary barriers taketime to set up, restrict both desirable and undesirable maritimetraffic, and are, by nature, passive defenses. Deployable nets, eithershot from some launching apparatus or dropped into the water by a boator aircraft, have limited range, cover a limited area, and require thetarget vessel to collide with the nets in order to be effective.

There is a need for an improved surface vessel arrestment system andmethod for impeding the motion of a surface vessel.

SUMMARY OF THE INVENTION

According to one aspect of the current invention, a projectile comprisesan airbag; a trigger mechanism adapted to activate inflation of theairbag; and a sensor adapted to detect impact of the projectile in thewater or on a surface and to trigger the trigger mechanism to activateinflation of the airbag.

According to another aspect of the current invention, a system forimpeding motion of a surface vessel comprises a projectile having asensor, a triggering device, and an airbag, wherein the sensor isadapted to determine an appropriate time to inflate the airbag, and thetriggering device receives a signal from the sensor to activateinflation to the airbag.

According to a further aspect of the current invention, a method forimpeding motion of a surface vessel, comprises directing a projectiletoward a hull of the surface vessel; detecting either contact of theprojectile with water or contact of the projectile with a surface; andinflating an airbag when the projectile is disposed in a position underone side of the surface vessel.

The above and other features of the invention, including various noveldetails of construction and combinations of parts, will now be moreparticularly described with reference to the accompanying drawings andpointed out in the claims. It will be understood that the particularassembly embodying the invention is shown by way of illustration onlyand not as a limitation of the invention. The principles and features ofthis invention may be employed in various and numerous embodimentswithout departing from the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is made to the accompanying drawings in which is shown anillustrative embodiment of the invention, from which its novel featuresand advantages will be apparent, wherein corresponding referencecharacters indicate corresponding parts throughout the several views ofthe drawings and wherein:

FIG. 1 is a schematic view of an airbag projectile according to anexemplary embodiment of the current invention; and

FIGS. 2A through 2C show pictorial representation of the airbagprojectile of FIG. 1 deployed to impede a surface vessel, according toan exemplary embodiment of the current invention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplatedmodes of carrying out exemplary embodiments of the invention. Thedescription is not to be taken in a limiting sense, but is made merelyfor the purpose of illustrating the general principles of the invention:the scope of the invention is best defined by the appended claims.

Broadly, the current invention provides a projectile that can be firedat a surface vessel, typically at surface vessels under 25 feet. Atimpact, an air bag may be deployed almost instantaneously fromunderneath the vessel. Through the rapid inflation of the air bag, thestability and orientation of the target surface vessel may be disturbed.Disturbance, at a minimum, may reduce and change the trajectory of thesurface vessel, but, in some circumstances, the surface vessel may beoverturned. The air bag may be designed with an anti-slip coating todirectly couple to the wet hull of the surface vessel. In someembodiments, the projectile may include a delay to enable the air bag tobe positioned under the vessel before inflation thereof.

Referring now to the drawings, and more particularly to FIG. 1, anairbag projectile 10 may include an airbag portion 12 and a triggeringmechanism 14. The airbag portion 12 may include an airbag 16. The airbag16 may be, for example, a nylon conical bag containing threechemicals—sodium azide 18, potassium nitrate 20 and silicon dioxide 22.While FIG. 1 shows the chemicals 18, 20, 22 as discrete elements in theairbag 16, typically, the chemicals 18, 20, 22 may be mixed togetherinside the airbag 16. The chemicals 18, 20, 22 may be in a mole ratio of2:2:1, respectively.

A heating element 24 may be disposed to warm the sodium azide 18 toabout 300 C, at which point the sodium azide may decompose into sodiumand nitrogen gas. The other chemicals 20, 22 in the airbag 16 may reducethe reactive sodium metal into an inert alkaline silicate, producingmore nitrogen gas in the process. These reactions may be rapid,inflating the airbag 16 in less than a second.

The heating element 24 may be powered by electrical means, for example,by a battery 26 connected to the heating element 24 by wires 28. Thewires 28 may pass through the airbag 16 and may break apart to separatethe airbag 16 from the battery 26 when the airbag 16 is inflated.

The triggering mechanism 14 may include a sensor 30. The sensor 30 maydetect impact of the projectile 10 into water 54 or may detect impact ofthe projectile 10 onto a surface, such as a hull 50 of a surface vessel52 (see FIGS. 2A-2C). The triggering mechanism 14 may further include atime delay mechanism 32. The time delay mechanism 32 may provide a delaybetween activation of the sensor 30 and energizing the heating element24. For example, if the sensor 30 detects that the projectile 10 hasjust entered the water, there may be a short delay (for example 0.5 toabout 5 seconds) to permit the projectile 10 to be disposed directlyunder one side of the surface vessel 52. The time delay mechanism 32 mayprovide a shorter or no delay if the sensor 30 detects that theprojectile 10 has impacted on a surface.

The airbag 16 may be housed in a housing 34. The housing 34 may protectthe airbag 16 while the projectile 10 is launched to be positioned underthe surface vessel 52. The housing 34 may be designed to break apartwhen the airbag 16 is inflated. The airbag 16 may contain an anti-slipcoating 36. The anti-slip coating 36 may permit the airbag 16 todirectly couple to the hull 50 of the surface vessel 52.

Referring now to FIG. 2A, the projectile 10 may be directed toward anunderside of one side of the surface vessel 52. Upon impact with thehull 50 of the surface vessel 52 (or after a previously determined timedelay after impact with water), the airbag 16 will rapidly (typically inabout one second or less) inflate, as shown in FIG. 2B. The anti-slipcoating 36 may cause the inflated airbag 16 to stick to the hull 50 ofthe surface vessel 52. Due to its buoyancy, the inflated airbag 16 willtend to rise to the surface of the water 54, impeding the surfacevessel's 52 motion, as shown in FIG. 2C. In some embodiments, thebuoyancy of the airbag 16 may cause the surface vessel 52 to overturnand capsize.

The projectile 10 may be launched toward the surface vessel 52 throughthe air or through the water. The projectile 10 may be launched usingeither energetic material or compressed gas, for example. The projectile10 may be instrumented into unmanned autonomous vehicles (AUVs, notshown). In some embodiments, the AUV system may be particularly usefulin a port security environment.

It will be understood that many additional changes in the details,materials, steps and arrangement of parts, which have been hereindescribed and illustrated in order to explain the nature of theinvention, may be made by those skilled in the art within the principleand scope of the invention as expressed in the appended claims.

The foregoing description of the preferred embodiments of the inventionhas been presented for purposes of illustration and description only. Itis not intended to be exhaustive nor to limit the invention to theprecise form disclosed; and obviously many modifications and variationsare possible in light of the above teaching. Such modifications andvariations that may be apparent to a person skilled in the art areintended to be included within the scope of this invention as defined bythe accompanying claims.

1. A projectile for impeding a surface vessel on water, said projectilecomprising: an airbag in stowed configuration, said airbag beinginflatable by reactive chemicals; a trigger mechanism for initiatingreaction of said chemicals thereby causing inflation of said airbag; anda sensor for detecting impact of the projectile in the water and totrigger said trigger mechanism to inflate said airbag under the wateradjacent the vessel.
 2. The projectile of claim 1, further comprising atime delay mechanism adapted to delay triggering of said triggermechanism responsive to said sensor detects the impact of theprojectile.
 3. The projectile of claim 1, further comprising a heatingelement for heating at least one of said chemicals in said airbag. 4.The projectile of claim 3, further comprising a battery for providingelectrical current to energize said heating element.
 5. The projectileof claim 1, wherein said chemicals include sodium azide, potassiumnitrate and silicon dioxide disposed within said airbag.
 6. Theprojectile of claim 1, further comprising a housing encasing saidairbag.
 7. The projectile of claim 1, further comprising an anti-slipcoating on an exterior surface of said airbag.
 8. A system for impedingmotion of a surface vessel on water, comprising: a projectile having asensor, a triggering device, and an airbag, wherein said sensor isadapted to determine an appropriate time to inflate said airbag, andsaid triggering device receives a signal from said sensor to inflatesaid airbag under the water adjacent the vessel.
 9. The system of claim8, further comprising a time delay mechanism adapted to delay triggeringof said trigger mechanism responsive to said sensor detecting impact ofthe projectile on the water.
 10. The system of claim 8, furthercomprising a heating element for heating at least one of said chemicalsin said airbag.
 11. The system of claim 10, further comprising a batteryfor providing electrical current to energize said heating element. 12.The system of claim 8, further comprising an anti-slip coating on anexterior surface of said airbag.
 13. A method for impeding motion of asurface vessel, the method comprising: directing a projectile toward ahull of the surface vessel; detecting either contact of the projectilewith water or contact of the projectile with a surface; and inflating anairbag when the projectile is disposed in a position under one side ofthe surface vessel.
 14. The method of claim 13, further comprisingdelaying the step of inflating the airbag for a predetermined period oftime after the step of detecting either contact of the projectile withwater or contact of the projectile with the surface.
 15. The method ofclaim 13, further comprising heating at least one chemical inside theairbag to initiate inflation of the airbag.
 16. The method of claim 13,further comprising coupling the airbag, after inflation thereof, to thehull of the surface vessel with an anti-slip coating disposed on anexterior surface of the airbag.
 17. The method of claim 13, furthercomprising capsizing the surface vessel due to buoyancy of the airbaginflated under one side of the surface vessel.